Grey's AnatomySeason 9, Episode 23: "Readiness Is All" was a punch in the gut to fans of Callie (Sara Ramirez) and Arizona (Jessica Capshaw) fans. After struggling all season, they finally seemed back on track and then — WHAM. Out of nowhere Arizona cheated. We were left screaming at our TVs. WHAT? WHY?

Read spoilers at your own risk! For more on Wetpaint Entertainment's philosophy on spoilers, clickhere.

Um...WHY? Jessica admitted that she was originally "completely shocked" by this storyline, a sentiment we echo. "But there was something about this, when Shonda and I were talking, that seemed like it rang true," she explained. After everything Arizona has been through this season "she had almost been reborn in this strange was as this new, but the same, person." And apparently that means doing things she wouldn't have done in the past.

Jessica insists that this story actually ties in well with the real-life experiences of people who go through life-changing events like Arizona's loss of her leg. "A lot of times they find themselves six months or a year post doing things that they would never have done before, and somehow being driven by this other feeling or this differentness that now lives in them."

But did it have to be cheating? Couldn't she have, we don't know, taken up a new hobby or something?

Jessica points out, though, that part of what's going on is that Arizona is surprised and maybe thrilled to discover that someone (who wasn't already in love with her) still finds her attractive, even though she doesn't have one of her legs. She also adds that for Arizona, this was a "crime of passion" — a moment of not thinking.

So, what next? "It's devastation," Jessica warns when asked about what's coming up for Calzona in the finale. "It's so heartbreaking. This is their defining moment." We know there's a Calzona scene that left all of the actors stunned at the finale table read, which makes us very nervous.

For much more from Jessica, check out the full interview. And please, vent your feelings about this twist below.